Induction system, especially for use as an induction port of an internal combustion engine

ABSTRACT

An intake assembly with an optimal noise level, especially an intake duct for use as the manifold of an internal combustion engine. The noise level is optimized by introducing shunt resonators ( 16, 18 ) in collecting manifold of the intake duct, which is produced using a multi-shell technique. The inserted structures ( 16, 18 ) can be adhered or welded before the shells are joined, or they can be inserted in a preexisting duct formed of previously joined half shells. The shunt resonators ( 16, 18 ) require little space and can also be used for subsequently optimizing the intake ducts in the test phase, if the initial test results are acoustically unsatisfactory.

BACKGROUND OF THE INVENTION

The invention relates to an air intake system, especially for use as anair intake duct of an internal combustion engine.

Air intake systems for internal combustion engines are provided withshunt resonators especially in the area of the intake tube in order tosuppress the air intake noise. In the simplest case these shuntresonators consist of a resonator chamber and a resonator neck whichconnects the resonator chamber to the intake tube. This basic form ofthe shunt resonator can be varied according to the particularapplication. It is conceivable to have several necks which havedifferent lengths to make it possible to dampen air intake noises ofdifferent frequencies. The resonator chamber can have almost any desiredshape.

A disadvantage in the use of shunt resonators is the space they requirein the area of the air intake tube. This must be provided in the motorcompartment, which is difficult due to the restricted space in the motorcompartment. An approach to the solution of the problem is to be found,for example, in DE 3842248 A1. A resonator is proposed which isintegrated into the housing of the air intake system. In this manner itis possible to use the dead space present in the housing as a resonatorchamber. Therefore there is no need to provide additional installationspace in the motor compartment.

The above-described resonator chamber must, however, be given attentionstructurally when establishing the configuration of the intake tubehousing. It is disadvantageous that the resonator described cannot beused to improve the acoustics of an existing intake tube if the resultsin regard to the intake noise of the intake tube are unsatisfactory. Insuch a situation there often is no more room in the motor compartmentfor a shunt resonator, since the development of the vehicle in questionis nearly completed. Thus an expensive new design may be necessary inthe intake tube area.

SUMMARY OF THE INVENTION

The object of the invention is to provide a Helmholz resonator whichrequires little space for its installation and can also be insertedsubsequently into an already existing intake tube structure. At the sametime either special frequencies of the intake noise are to be damped ora broad-band damping is to be achieved.

ADVANTAGES OF THE INVENTION

The object is achieved in accordance with the invention in that aninternal structure is placed in the interior of the intake tube andfastened there. This internal structure forms together with the walls ofthe intake tube a resonator chamber which must have at least one openinginto the interior volume of the intake tube. Such an internal structurerequires no additional installation space in the motor compartment.Furthermore, the possibility of retrofitting is an advantage. Above allthis is easy to accomplish in air intake tubes which are manufactured bythe multiple shell technique. Likewise, however, such an internalstructure can be installed through the inlet and outlet openings of theintake tube. At the same time the shape of the intake tube need not bechanged or need only be changed to an insubstantial extent. If theinternal structure has been glued in, for example, it need only beadapted to a certain contour area of the intake tube. Advantageously,the internal structure can be configured in such a way that, afterinstallation in the intake tube, it produces several resonator chambersof different volume. By this means different frequencies can be dampedat points of concentration in the intake area.

One practical variant of the invention envisions installation of theinternal structure in the interior of the air intake tube. It isarranged ahead of the air intake ducts to the cylinders. Therefore thenoise damping acts on all of the air intake ducts of the air intaketube.

According to one practical embodiment of the internal structure, it isconstructed of a flat component, e.g., a perforated plate, and spacers.The resonator chamber is accordingly produced between the perforatedplate and the wall of the intake tube. It is advantageous in this casethat the internal structure can be produced from simple semi-finishedproducts. This leads to an economical improvement in the case of smallseries, e.g., in the tuning area.

An alternative variant of the internal structure envisions configuringit as an insert. It can be made in one piece with a positive influenceon economy in large series production.

In accordance with a further embodiment of the invention the internalstructure can have areas of differing wall thickness. If a plurality ofopenings are provided in an internal structure, then different necklengths will result for the shunt resonator. The positive effect of thisembodiment is a broad-band damping of the air intake noise.

On condition that the internal structure and the air intake tube arecomposed of the same material, the internal structure can also be weldedinto the air intake tube. This applies in particular to synthetic resinintake tubes, however it is also conceivable for metal intake tubes. Asynthetic resin insert can be installed especially by ultrasonic weldingmethods. In any case other welding methods are also possible, as forexample friction welding.

These and additional features of preferred embodiments of the inventionwill be found not only in the claims but also in the description and thedrawings, and the individual features can each be realized by itself ortogether in the form of subcombinations in the embodiment of theinvention and in other fields, and can constitute advantageous as wellas independently patentable embodiments, for which protection is herebyclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional details of the invention are described in the drawings withreference to schematic embodiments.

FIG. 1 shows a section through an air intake tube for an internalcombustion engine with an in-line arrangement of the cylinders, with thetypical spiral course of the air intake passage, taken along line A—A inFIG. 2.

FIG. 2 shows the section B—B according to FIG. 1 taken through themanifold of the air intake tube with a view of an insert structureacting as a shunt resonator and the openings of the air intake ports.

FIG. 3 shows a schematic section through the wall of an internalstructure with variable wall thickness and bores which serve as necks ofdifferent length for the resonator, and

FIG. 4 shows a schematic section through an insert structure for theproduction of two resonator chambers of different volume.

DESCRIPTION OF PREFERRED EMBODIMENTS

In FIG. 1 an air intake tube 10 is shown in section through one of theair intake ports 11. The combustion air is fed to a manifold chamber 12through an inlet which is not shown. The manifold chamber distributesthe combustion air to the air intake ducts 11 which are connectedthrough outlets 13 to the air inlets, which are not shown, at thecylinder end. The combustion air is fed through these to the motor. Deadspaces 14 arising in the air intake tube can be utilized for damping ofthe intake noise.

The air intake tube is composed of several shells 15. Before the shellsare welded together, internal structures 16 can be brought intoconnection with internal walls 17 of the air intake tube. The internalstructures have bores 18 which serve as necks for the resonator chambersformed by the internal structures. The internal structures preferablycan be mounted in the manifold chamber 12 of the intake tube.

The internal structures 16 can be made of a perforated sheet metal 19and spacers 20 which are disposed between the inner wall 17 and metalsheet 19. Alternatively, the internal structure can comprise a singleinsert piece 21 which is preferably welded to the internal wall 17. Forthis purpose welding recesses 22 must be provided on the internal wall.The welding of the shells 15 takes place after the installation of theinternal structures 16.

In FIG. 2 the manifold chamber 12 is shown in a longitudinal section. Itestablishes the connection of an inlet 24 for the combustion air and theair intake ports 25.

The internal structure 16 is shown in plan. In this drawing thecomparatively large size of the surface in comparison with the height ofthe internal structure (compare FIG. 1) is clearly seen. This geometryis necessary, since the cross section of the manifold chamber must notbe excessively narrowed. In this manner a sufficient supply of air isdelivered to the air intake ports.

FIG. 3 depicts a section through the wall section of an internalstructure 16. The wall thickness of the component increases linearly inthis case. The bores 18, which are made at regular intervals in the walland serve as necks of the shunt resonator, have a varying length. Inthis way the shunt resonator has a broad-band effect.

FIG. 4 shows schematically an internal structure 16 with severalresonator chambers 23. These are formed by a dividing wall 26 whichrests on the inner wall 17 of the air intake tube. The internalstructure can be attached to the intake tube wall via a circumferentiallip 27.

What is claimed is:
 1. An air intake assembly comprising: an air intakeduct for an internal combustion engine, said intake duct comprising aninlet, at least one outlet, and having cavity-forming inner wallsdefining a duct geometry, and at least one internal structure arrangedinside said air intake duct, wherein said internal structure can beintroduced into a preexisting intake duct while at least substantiallyretaining the duct geometry, said internal structure being attached tothe cavity-forming inner walls and in cooperation with said inner wallsenveloping at least one resonator chamber, and said at least oneresonator chamber having at least one opening communicating between saidresonator chamber and said air intake duct.
 2. An air intake assemblyaccording to claim 1, wherein said internal structure is adhesivelybonded to said internal walls.
 3. An air intake assembly according toclaim 1, wherein said internal structure is welded to said internalwalls.
 4. An air intake assembly according to claim 3, wherein saidinternal structure is ultrasonically welded to said internal walls. 5.An air intake assembly according to claim 1, wherein said at least oneopening comprises at least one bore through a wall of said internalstructure.
 6. An air intake assembly according to claim 1, wherein theat least one internal structure is disposed in a manifold chamber.
 7. Anair intake assembly according to claim 6, wherein said flat plate is aperforated sheet metal plate.
 8. An air intake assembly according toclaim 6, wherein said internal structure is a one-piece insert.
 9. Anair intake assembly according to claim 6, wherein said internalstructure has areas of differing wall thickness, and at least twoopenings are provided in respective areas of differing wall thickness.10. An air intake assembly according to claim 9, wherein said at leasttwo openings comprise at least two bores through a wall of said internalstructure.
 11. An air intake assembly according to claim 1, wherein saidinternal structure comprises a flat plate and at least one spacerdisposed between said flat plate and the inner wall of the cavity. 12.An air intake assembly according to claim 1, wherein said internalstructure is a one-piece insert.
 13. An air intake assembly according toclaim 1, wherein said internal structure has areas of differing wallthickness, and at least two openings are provided in respective areas ofdiffering wall thickness.
 14. An air intake assembly according to claim13, wherein said at least two openings comprise at least two boresthrough a wall of said internal structure.
 15. An air intake assemblyaccording to claim 1, wherein said air intake duct and said internalstructure are formed of the same material.
 16. An air intake assemblyaccording to claim 15, wherein said air intake duct and said internalstructure are both formed of the same synthetic resin material.